(Meth)acrolein or (meth)acrylic acid is usually produced using a multitube reactor through a vapor-phase catalytic oxidation reaction of propylene, propane or isobutylene in the presence of a mixed oxide catalyst using molecular oxygen or a molecular oxygen-containing gas. (Meth)acrolein or (meth)acrylic acid can be obtained from a resulting reaction gas through a collecting method using a collecting solvent.
Example of a conventional method for collecting (meth)acrolein or (meth)acrylic acid from a gas containing (meth)acrolein or (meth)acrylic acid using a solvent includes collecting method using water or an aqueous solution as a collecting solvent. Example of such a collecting method includes a known technique involving cooling a large volume of a gas by adjusting a composition of an aqueous solution used for collecting, to thereby collect (meth)acrolein or (meth)acrylic acid (see JP 09-157213 A, for example).
The conventional method for collecting (meth)acrolein or (meth)acrylic acid from a gas containing (meth)acrolein or (meth)acrylic acid using an aqueous solution has problems in that (meth)acrolein or (meth)acrylic acid was not even partially collected and was discharged along with a reaction gas because of a very large volume of the reaction gas supplied to a collecting device.
Meanwhile, example of the method for collecting (meth)acrolein or (meth)acrylic acid using a solvent includes another known technique involving cooling a large volume of a gas by adjusting a shape of or arranging method for internals of a collecting device, to thereby collect (meth)acrolein or (meth)acrylic acid (see JP 2001-019655 A, for example).
The method employing high performance packing for internals of the collecting device is not sufficient because when a collecting tower is used as the collecting device, an increase of acrylic acid distilled to a top of the collecting tower due to operational fluctuation of the tower easily causes clogging through polymerization of acrylic acid.